The present invention relates to electric appliances, namely vacuum cleaners.
Vacuum cleaners work by suction. An electric motor in the cleaner drives a fan that pumps air from a chamber within the cleaner to create a vacuum. This vacuum is employed to draw air laden with dust and dirt from a surface into a dust bag or into a collection compartment within the cleaner which retains the dirt and dust. The air is expelled through an outlet in the body of the cleaner.
Typically, there are two types of vacuum cleaners, the cylinder vacuum cleaner and the upright vacuum cleaner. In the cylinder vacuum cleaner, a flexible hose connected to a cleaning attachment is provided and the cleaning attachment is passed over a surface to be cleaned to draw air laden with dirt and dust into the collection compartment or dust bag via the hose. In the upright vacuum cleaner, air is drawn into the collection compartment or dust bag through an inlet in a base or foot unit which comprises wheels to allow the cleaner to be pushed and pulled over the surface to be cleaned. To further improve the cleaning action of the cleaner, a rotating brush is provided across the inlet in the base unit that beats dirt and dust out of the surface to be cleaned. Some upright cleaners are also provided with a flexible hose and cleaning attachment like the cylinder type for the purpose of cleaning surfaces such as floors and upholstery, and means for switching suction between this and the base unit of the cleaner.
Conventional vacuum cleaners of both types are effective in drawing in dirt and dust from the surfaces on which the cleaning attachment or base unit is used. However, they do not draw in airborne particles of dirt and dust. Indeed, the very act of vacuuming can cause large quantities of dirt and dust to become airborne, thereby avoiding the cleaning action of the vacuum cleaner. In this regard, air expelled from the vacuum cleaner blows dirt and dust into the air, movement of the cleaning attachment or base causes dirt and dust to become airborne and even the movement of the operator can raise dirt and dust into the air. The presence of these airborne particles of dirt and dust can be a problem for those people who have dust allergies.
It is an object of the present invention to provide a vacuum cleaner which draws airborne particles of dirt and dust into the cleaner.
According to the present invention there is provided a vacuum cleaner comprising: a body which houses a container in which is collected dirt and dust. A surface cleaning head defines a primary dirt and dust collection inlet able to contact, in use, a surface over which the surface cleaning head is moved. A passageway connects the primary inlet to the container. A secondary dirt and dust collection inlet is remote from the primary inlet and spaced, in use, from the surface. Suction means draw dirt and dust through the primary and secondary inlets into the cleaner. The primary inlet is adapted to draw surface-borne dirt and dust efficiently into the cleaner and the secondary inlet is adapted to draw airborne dirt and dust efficiently into the cleaner.
Airborne particles of dirt and dust from around the cleaner may be sucked into the cleaner by the secondary inlet(s). The advantage of this is that dirt and dust are removed from the room environment and not just from the surface.
There may be only one secondary inlet, in which case it is preferably in the form of a slot. Preferably, however, there is an array of secondary inlets.
The relative cross sections of the first and second inlet can be used to balance the performance of each inlet. Preferably, the cross section of the second inlet is less than two hundred percent (200%) of the cross section of the first inlet, ideally less than one hundred percent (100%). Preferably, the cross section of the second inlet is greater than five percent (5%) of the first inlet, preferably greater than ten percent (10%).
In a preferred embodiment adjustable dampening means may be provided to the first inlet, the second inlet or both first and second inlets so as to adjust the performance of each inlet. Operator adjustments to performance can then be made to adjust the vacuum cleaner to differing cleaning environments, for example, carpet type, room size, levels of dust etc. In a further embodiment, the dampening means may be controlled by an actuator, which may be activated directly or indirectly by the operator to pre-set positions. Electronic control means may be used within the vacuum to control the actuator(s). Sensors may be present in the vacuum cleaner to feed information into the electronic control means which may automatically adjust the dampening means via the actuator(s) during operation in response to the sensor information. Sensors may detect air flow, pressure or levels of dirt.
The dampening means may be any suitable feature known to open or close air inlets, for example, a slideably mounted inlet shutter, air valve, constricting/dilating passageway or a switch to the suction means or any combination thereof.
The electronic control means includes any conventional solid state system or circuit board able to process information input from any optionally present sensor or from the operator and effect a change directly to the dampening means or indirectly to the dampening means via the actuator(s).
In an alternative embodiment, the dampening means are provided to the first and second inlet and are independently able to fully open and fully close, or any position in between, each inlet. Such an orientation of the device allows the vacuum cleaner to be switched between solely taking in air from the primary inlet or the secondary inlet or in any proportion in between.
The secondary inlet(s) may be connected into the passageway connecting the surface cleaning head to the dust and dirt collection compartment in which case both the surface cleaning head and the secondary inlet(s) may share a common suction means. Alternatively, a separate passageway, or passageways, may be provided to connect the secondary inlet(s) to the dust and dirt collection compartment. In this latter case, it may be convenient to provide separate suction means for each passageway.
Suction means will invariably involve an electric motor and/or a fan. These components are conventional in the field to draw the air through the cleaner. The suction means may draw the air through both inlets by way of a single motor drawing air through both inlets or two motors one for each inlet. A single motor could simultaneously draw air through both inlets by driving a fan in each inlet.
In a preferred orientation of the single motor in which the second inlet is connected to the passageway of the first inlet, the cross-sectional area of the secondary inlet relative to the cross-section of the primary inlet will primarily determine the relative air flows between the two inlets.
Dust filtering means, such as an electrostatic filter, may be provided between the secondary inlet(s) and the compartment. This may be appropriate when the air drawn into the secondary inlet(s) (xe2x80x9csecondary airxe2x80x9d) is conveyed over the suction means or part of it (that is, over a fan and/or motor). This may be done to effect cooling. Preferably, however, secondary air is not thus conveyed. Preferably, also, no such dust filtering means between the secondary inlet(s) and the compartment is provided.
With upright vacuum cleaners typically having a wheeled base unit which contains the primary inlet, and articulated to an upright main body which contains the dirt and dust container, there is preferably a plurality of secondary inlets provided in an upper surface of the base unit or in the main body thereof, or in both. With cylinder vacuum cleaners, typically having a single, generally drum shaped, a wheeled body and carrying a cleaning head comprising the primary inlet on a flexible tube, there is preferably a plurality of secondary inlets provided in the body thereof, preferably in the upper region thereof. Alternatively or additionally one or more tubes may extend over the outer casing of the vacuum cleaner, whether of upright or cylinder type, and include a plurality of secondary inlets therein at intervals along its length through which airborne particles of dirt and dust can be drawn. In one such embodiment of the present invention, such a tube extends in a helix around the main body or on the upper surface of the vacuum cleaner.
Preferably the secondary inlets of an array are reasonably well spaced from each other.
Preferably, the secondary inlets of an array are not unidirectional. Unidirectional, in this situation, means all facing in the same direction.
Preferably, at least one secondary inlet of an array faces generally forwards.
Preferably, at least one secondary inlet of an array faces generally rearwards.
Preferably, at least one secondary inlet of an array faces generally sideways.
Preferably, at least one secondary inlet of an array faces generally sideways in one direction and at least one secondary inlet of an array faces generally sideways in the opposite direction.
If wished, at least one secondary inlet of an array faces generally upwards.
Suitably there are at least three (3) secondary inlets in an array, preferably at least five (5), more preferably at least eight (8), and most preferably at least ten (10).
Alternatively or additionally, a secondary inlet may be in the form of a single slot that is not unidirectional. Unidirectional, in this situation, refers to a straight slot provided in a planar face.
Preferably, a secondary inlet in the form of a single slot has a portion which faces generally forwards.
Preferably, a secondary inlet in the form of a single slot has a portion which faces generally rearwards.
Preferably, a secondary inlet in the form of a single slot has a portion which faces generally sideways.
Preferably, a secondary inlet in the form of a slot has a portion which faces generally sideways in one direction and a portion which faces generally sideways in the opposite direction.
A secondary inlet in the form of a slot may extend substantially all the way around the cleaner, such that it can draw in airborne dirt and dust from the front, rear and both sideways directions. Thus, it could be an endless slot or a generally helical slot.
If desired, a secondary inlet in the form of a single slot has a portion which faces generally upwards.
The words xe2x80x9cforwardsxe2x80x9d, xe2x80x9crearwardsxe2x80x9d, xe2x80x9csidewaysxe2x80x9d and xe2x80x9cupwardsxe2x80x9d are used herein with reference to the vacuum cleaner in its normal configuration and orientation in use, with the cleaning head at the front but are not meant to be limiting.
In accordance with a second aspect of the present invention there is provided a method of cleaning using a vacuum cleaner of the invention as defined herein, whereby dust and dirt are drawn in from a surface through the primary inlet and from the air by the secondary inlet.